Cord and method of making same



June 18 1940. J. E. FARR'E'LL 2,205,285

CORD AND METHOD OF MAKING SAME Filed March 2, 1939 M L ALL Patented June 18,

UNITED STATES PATENT OFFICE poration of Alabama Boylston Mfg Company of Alabama, a cor- Applieation March 2, 1939, Serial No. 259,316

12 Claims.

The invention relates to cord, such as used in automobile tires, belting, and the like, where tensile strength, elongation substantially proportional to tensile stress, and great flexibility are of 6 prime importance, and relates also to the method of forming such cord. The objects of the invention are to provide a new and valuable method of producing such cord, and of course the cord so made, wherein tensile strength will be as nearly 10 as possible the sum of the tensile strengths of the individual fibres at any cross section, the elongation as nearly as may be proportional to tensile stress, and the flexibility at the highest obtainable maximum. The objects of the invention are" well attained in the method and product to be described, which results in a cord of remarkable tensile strength, practically uniform elongation under tensile stress, and last but not least probably the maximum obtainable flexibility.

To those familiar with the conditions obtaining in automobile tires the value of these qualities will be manifest.

To attain the objects of the invention I utilize to the greatest possible extent the natural, or

rather the predominating twist of the fibres, as clearly indicated in the drawing.

In the drawing Fig. 1 is a diagram showing the method of forming the spun yarn from the fibres, Fig. 2 a similar diagram showing the formation 0f the ply yarn, while Fig. 3- illustrates the final step, the formation of the cord, or cabling of the ply yarns.

While other fibres may be available the invention mainly contemplates and has been designed as for the making of cords of cotton. As well understood the fibre of cotton is-a relatively long, pipelike, filament, somewhat resembling a flattened firehose, and, particularly if of good grade, considerably twisted. The twist is not uniform 40 usually in any single fibre but in the majority of fibres of good grade the predominant twist is of one direction, as clock-wise in thebetter American cottons, and the extent of twist also varies in cottons from other sources, for example the 4;; Egyptian cotton fibre is usually more twisted than that of American Delta cotton. Cotton fibres without a predominant twist are not suitable for the invention, but there is no difficulty in obtaining sufiicient cotton with sufllciently predominant twist. The predominant twist may be clock-wise or counter-clock-wise, as the invention applies equally to both twists. As the American cotton available usually has the predominant twist clock-wise, or right-hand, the invention can be described as used with fibre of this kind, the necessary reversal if a left-hand twist fibre is em ployed being obvious.

The first step in the method, intended to develop as nearly as possible a tensile strength substantially that of the sum'of the tensile strengths of the individual fibres in any cross-section, to condense the cord, and to permit the development of flexibility by subsequent steps, is the formapredominant twist of the fibres. This twisting is, preferably, of such extent that the spun yarn 3 is, when finished, practically "cabled," or neutral, that is to say the reverse twist given the spun yarn, opposed by the natural predominant twist of the fibres, renders the spun yarn largely neutral, and without tendency to unravel. The lack of tendency to unravel is, however, of less importance than the maximum intimate intertwin ing of the fibres so produced by this reverse winding in forming the spun yarn. The overlapping fibres, so twisted together in opposition to the predominant natural twist, are frictlonally engaged to the greatest possible extent, so much so that the tensile strength of the spun yarn closely approximates the sum of the tensile strength of adjacent fibres in any cross section. In other words the fibres are twisted together in the most eflicient manner, and if the predominant natural twist was exclusive of any reverse twist in the fibre, the bonding of fibres would be at the theoretical maximum. With a fibre having only right-hand twist this result would obtain from a left-hand twist in forming the spun yarn. Taking cotton as we find it the bonding falls short to an unavoidable extent but still produces the strongest spun yarn that can be made of the particular fibre used. It will be obvious that the amount of twisting given the spun yarn bears a relation to the predominant natural twist of the fibres, and the spun yarn, while formed of well bonded fibres, will not be strictly neutral, or exactly cabled, if given a twist in excess of the predominant natural twist of the fibres.

The twisting'of fibres into the spun yarn can be done by any suitable means known in the art, and in Fig. l I have merely shown at-l, l, two strands of fibres, assumed to have predominant natural twist clock-wise, as indicated by the small circular arrows, 2, 2, as being twisted together into the spun yarn, 3, with a counter-clock-wise twist as indicated by circular arrow 4.

Having obtained these approximately neutral spun yarns, formed, it will be remembered, with counter-clock-wise twist, I then form the ply yarn by twisting together a plurality of the spun yarns, the twist here being also counter-clockwise, as indicated in Fig. 2, where 5, 5, are two spun yarns, the arrows 6, 6 indicating the direction of their twist, are shown as being twisted into a ply yarn, 1, the twist being counter-clockwise, and the completed ply yarn being unstable. not neutral, and with a tendency to unravel.

A plurality of ply yarns so obtained are then wound together to form a cord, and here the winding, for obvious reasons, is reversed or clockwise. This is the direction of twist, or rather predominant twist, of the fibres. The final twisting together of the ply yarns in clock-wise direction. is so governed that the complete cord is neutral, that is to say stable, and with no hurtful tendency to unravel.

The winding of the spunyarns in the same di-" rection in which are wound the ply yarns is of great importance in obtaining the-extremely important maximum of flexibility in the finished cord. The final winding of the ply yarns into the cord, must, of course, be reversed, as explained, in order to render the cord neutral, and this is unavoidable. However, starting from the substantially neutral spun yarns, which have practically no tendency to unwind or unravel, and then winding the spun yarns so formed in the same direction into the ply yarn, has a most important effect upon the flexibility of the finished cord.

In practice I find the cord distinctly stronger by test than cord made up by the usual process which, in the United States at least, consists in winding the spun yarns to the right, regardless of the predominant twist of the fibres, then winding the ply yarns to the right, and thencabling the ply yarns. My cord has greater ultimate tensile strength, indicating that it develops a stress resistance nearer the sum of the tensile strengths of the fibres in any one cross section;

has nearly a straight line characteristic on a tensile strength testing machine, indicating that the elongation is almost exactly proportional to the tensile stress; and possesses flexibility to a truly remarkable extent.

The method, viewed as a whole, is very simple. But, as indicated, in this very simplicity it takes full advantage of the predominant twist of thefibre, produces a superior spun yarn, and that had, by the steps of the method, produces a cord having qualities of the utmost value for the uses intended. Similarly the cord is equally simple. It merely starts with a fibre of predominant twist; that fibre twisted into spun yarns with a reverse twist, the spun yarns twisted into ply yarns with like reverse twist, and then the final cabling twist now in the direction of the predominant natural twist of the fibre. But the result is a cord of nearly theoretical maximum tensile strength, of almost completely uniform elongation, and with a most surprising degree of flexibility.

It will be understood that the number of turns per linear inch of spun yarn, ply yarn, and cord, can be so governed as will produce the best results from fibre of various degrees of predominant twist. The broad invention, however, is fully set forth above, and lies in the particular relation of the several actual twistings to the predominant natural twist of the fibre.

In the claims following a neutral yarn, or cord,

is taken as meaning a substantially stable yarn, or cord, the word neutral having its ordinary meaning as used with reference to ropes and cords. The term cabling is used as denoting that kind of winding which renders a finished cord or rope substantially neutral or stable, the

final "cabling, or completing twist, being reverse to that of the ply yarns or plies which makeup the cord or rope.

It is obvious that the fullest development of the invention would be had with a fibre, if there is any such, wherein the natural twist is all in one direction, for with such fibre a perfect spun yarn could be produced. Failing such a fibre the next best fibre is that in which the twist in one direction greatly predominates over that in the opposite direction, as in American Delta cotton, Egyptian cotton, and perhaps other cottons. The least result would be had, of course, with cotton without predominant natural twist; such cotton being-practically worthless for the purposes of this invention.

Having described the invention what I claim is:

1. The method set forth, which consists in utilizing the predominant natural twist of cotton fibres to form a substantially neutral spun yarn, twisting together a plurality of such substantially neutral spun yarns into a ply yarn with the same direction of twist as that of such spun yarns, and then cabling the ply yarns so formed into a substantially neutral cord, substantially as set forth.

2. The method set forth, which consists in twisting together into a spun yarn cotton fibres having a predominant natural twist opposite that employed in forming the spun yarn; then twisting such spun yarns into a ply yarn in the same direction employed iii forming the spun yarns;

then cabling the ply yarns so formed into a substantially neutral cord, substantially as set forth.

3. The method set forth, which consists in forming a spun yarn from cotton fibres having a predominant natural twist by twisting such fibres together in a direction opposite that of such predominant natural twist and to a predetermined extent necessary to form a substantially neutral spun yarn; forming a ply yarn from a plurality of such spun yarns by twisting such spun yarns together in a direction opposite that of such predominant natural twist and to an extent necessary to form an unstable ply yarn; then forming a cord from a plurality of such ply yarns by twisting such ply yarns together in a direction the same as that of said predominant natural twist and to an extent necessary to render said cord neutral, substantially as set forth.

4. The method set forth, which consists in forming a substantially neutral" spun yarn from cotton fibres having a substantially predominant natural twist by twisting together such fibres in a direction opposite that of such predominant natural twist and to an extent sufficient to render such spun yarn substantially neutral; then forming a ply yarn by twisting together a plurality of such spun yarns in the same direction as that of the twist of the spun yarns; then cabling the spun yarns into a cord with a twist the same as that of the predominant natural twist of the fibres, substantially as set forth.

5. As a new article of manufacture, a substantially neutral spun yarn formed of cotton fibres having a predominant natural twist and twisted together in direction the opposite of such predominant natural twist and to an extent sumcient to render the spun yarn substantially neutral, substantially as set forth.

6. As a new article of manufacture, a cotton cord, the fibres of which have a predominant natural twist, the spun yarns of which, have a twist the reverse of such predominant natural twist, the ply yarns of which have a twist the same as that of the spun yarns; and the cord itself having twist the reverse of that of the spun yarns and ply yarns, substantially as set forth.

'7. As a new article of manufacture, a cord the spun yarns of which are twisted in the reverse direction to that of the predominant natural twist of the cotton fibres, the ply yarns of which are twisted in the same direction as the spun yarns, and the cord itself twisted in the reverse direction to that of the spun yarns and the ply yarns, substantially as set forth.

8. As a new article of manufacture the substantially neutral spun yarn the twist of which is opposite in direction to that of the predominant natural twist of the fibres of which such spun yarns are made and sufficient to render the spun yarn substantially neutral.

9. The method described, of forming a cotton cord of substantially maximum tensile strength per weight of cord per unit of length, which consists in selecting a cotton the fibres of which have a substantially predominant twist and given tensile strength, then twisting aplurality of such fibres together into a spun yarn with a direction of twist opposed to such substantially predominant twist and to such extent as to develop substantially maximum frictional engagement between adjacent fibres in such spun yarn, then twisting a plurality of such spun yarns into 9. ply yarn with the same direction of twist used in forming the spun yarns, and then cabling a plurality of such ply yarns by twisting them together with a direction of twist opposite that employed in forming said spun and ply yarns, substantially as set forth.

10. The method described of obtaining approximately the sum of the tensile strengths of individual fibres in a cord, which consists in selecting a cotton fibre having a pronounced natural twist in one direction, forminga spun yarn from such fibres by twisting them together in a direction opposed to that of such pronounced natural twist to such extent as to produce maximum bonding between adjacent fibres, and then forming ply yarns from such spun yarns and a cord from I such ply yarns, substantially as set forth.

11. The method set forth, which consists in selecting a cotton fibre suitable tensile strength and having a pronounced predominance of twist of one directon over twist of the opposite direction, then twisting such fibrestogether in such manner and to such extent as to produce maximum frictional engagement between adjacent fibres, and a substantially neutral spun yarn, then forming such spun yarns into ply yarns,

and such ply yarns into a cord, in which substantially every overlapping fibre is twisted around its adjacent neighbor to such extent that the tensile strength of any series of overlapping fibres is substantially as great as that of an individual fibre, substantially as set forth.

12. As a new article of manufacture a cord the individual fibres of which are so intertwined with reference to the direction of the predominating natural twist of the fibres that the frictional engagement of any one chain of overlapped fibres is approximately as great as the tensile strength of an individual fibre, substantially as set forth.

JAMES E. FARRELL. 

